The head of a police special operations unit in Turin,Giuseppe Petronzi, was hurt by an improvised explosive deviceduring the confrontation on Saturday night in Val di Susa in thefar north of Italy, when police fired teargas at supporters of"No-Tav", the anti high-speed rail movement.

"What happened last night in Val di Susa was not ademonstration of dissent, it was violence," Interior MinisterAnnamaria Cancellieri said in a statement.

The authorities would ensure that construction work could goahead, she added, pledging "maximum toughness" against violentdemonstrations.

The latest in a long line of clashes follows months ofconfrontations over the high-speed rail link which has become afocus for anti-establishment protests, fuelling concern over aspike in violent demonstrations during the economic crisis.

Video footage released by police showed young black-claddemonstrators hurling rocks and flares at squads of police inriot gear around a construction site in the thickly woodedmountain valley.

Politicians on all sides condemned the violence, but policeunion COISP accused the government of allowing the situation toget out of hand, threatening the life of officers.

"There is a criminal hunt against police going on in Val diSusa while the government continues to underestimate thesituation which is just waiting for someone to be killed," theunion said in a statement.

Villagers in Val di Susa, supported by a coalition ofoutside activists, have held repeated demonstrations against the15-billion-euro-project ($18 billion), agreed between Italy andFrance in 2001.

The government says the rail link, which will almost halvethe time of a journey between Paris and Milan to four hours, isvital to strengthen transport links between northern Italy andthe rest of the continent. ($1 = 0.8219 euros)